1. Field of Invention
The invention relates to an orthognathic planning system with a navigation function, and an orthognathic planning method.
2. Related Art
Clinically, there are many patients having special maxillofacial ratios or incorrect occlusal relationships between upper and lower rows of teeth. Such a kind of abnormally growth problem often accompanies with the facial asymmetry, the mandibular prognathism, the mandible retrusion or the poor occlusal condition on the organization structure. Regarding the life, the patient tends to encounter the stoppages, such as the pronunciation difficulties, the chewing digestive diseases, the lack of confidence, or even the other's discrimination and the people's strange looks.
In view of the above-mentioned problems, the general and effective treatment is to correct the spatial positions of the maxilla and mandible through the surgery and to reconstruct the good occlusal relationship. This kind of surgery is typically referred to as an orthognathic surgery. Because the object of the orthognathic surgery is to correct the upper facial structure of the jaw, such as the facial asymmetry, the facial harmonious proportion or the like, as well as the growth problem, or to correct the skeleton structure change, which cannot be easily or cannot be completed using braces. So, the detailed preoperative diagnosis has to be made such that the orthognathic surgery planning can be established in connection with the actual situation of the patient's maxillofacial skeleton structure, and the jawbone can be indeed moved to the proper position. Thus, this is referred to as the “orthognathic surgical planning”, “orthognathic planning” or “orthognathic surgery planning”, the quality of which significantly affects the quality of the surgical behavior.
In the past, when the orthognathic planning is performed, the doctor only relies on the cephalometric data on the photographed X-ray films of the front side and the lateral side of the patient's head, and then plans the postoperative jawbone position on the articulator. Because only the two-dimensional information is provided by the X-ray images of the front side and the lateral side, but a series of complicated processes including simulating the surgical osteotomy and manufacturing, moving the dental cast and the like have to be performed, the long-term problem that the orthognathic planning on the clinical practice has to rely on the experience and the technique of the main surgeon is caused. When the treatment is not smooth, or even the facial jaw is still slightly skewed although the patient's teeth have the precise occlusal relationships after the surgery, the satisfaction of the orthognathic surgery is affected.
To sum up, the generally existing problems of the conventional orthognathic planning can be generalized as follows. First, the lack of the planning synchronization between the teeth and the jawbone causes the perfect postoperative dentition occlusion but the unsymmetrical overview of the maxilla and the mandible. Second, it is too time-consumptive to perform the adjustment of transferring the cephalometric data to the physical plaster dental cast by way of try-and-error, and the occlusion and symmetry cannot be satisfied concurrently. Third, it is difficult to use the two-dimensional data to truly represent the three-dimensional spatial relationship between the midface and the mandible. Fourth, it is difficult for the orthognathic planning surgery program, mainly based on the occlusion with the aid of the X-ray cephalometric data, to achieve the overall symmetry of the facial jawbone.
Therefore, it is an important subject to provide an orthognathic planning system and an orthognathic planning method, which provide the operator the more precise data, especially the three-dimensional visible data, in the preoperative planning processes, so that the simulation result is closer to the real situation and assists the operator or doctor to achieve the preferred surgical planning target. In addition to avoiding the unnecessary consumption of the labor and time in the try-and-error processes, it is desired to be further advantageous to the reduction of errors, and the enhancement of the orthognathic surgical success rate.